Multimode Cw Dye Laser Research Articles

Measurement of high overtone intensities of HBr by two-tone frequency-modulation spectroscopy

The technique of two-tone frequency-modulation spectroscopy (TTFMS) using a multimode cw dye laser was employed to study high overtone bands of HBr. Individual vibration-rotational linestrengths and positions were measured. On the basis of these measurements, rotationless dipole moment matrix elements and Herman-Wallis coefficients were determined for the 6-0, 7-0, and 8-0 overtone bands. Using the rotationless dipole moment matrix elements obtained previously by other workers for the pure rotational, fundamental, and first four overtone bands, together with the present results and numerical vibration-rotational wavefunctions, we have derived a series expansion for the dipole moment function. This function provides an excellent fit to all existing Herman-Wallis coefficients, and thus represents one of the best known dipole moment functions for any diatomic molecule. The accuracy of the present data also confirms the importance and utility of TTFMS when used for performing ultrasensitive molecular spectrosocpic measurements of weak overtone bands.

Laser separation of lithium isotopes by double resonance enhanced multiphoton ionization of Li2

Multiphoton ionization spectra of 7Li2, 6Li2, and 7Li6Li vapors have been measured in the 570–650 nm region using a single, low resolution, multimode cw dye laser. A number of wavelengths provide selective multiphoton ionization of one isotopic species demonstrating the possibility of efficient laser-driven isotopic separation in lithium in this wavelength region.

Stimulated Brillouin scattering and dynamical instabilities in a multimode cw dye laser.

Stimulated Brillouin scattering in the dye jet inside a linear laser cavity has been investigated and found to be of significant importance for the dynamical behavior of multimode cw dye lasers. At high spectral power densities, it is responsible for a strong coupling of thousands of individual modes into a few mode packets, thus drastically reducing the number of actually existing degrees of freedom of the system. For a decreasing spectral power density, the mode-coupling strength due to stimulated Brillouin scattering lowers, accompanied by an increase of the number of mode packets. At low spectral power densities, additional mode-coupling mechanisms are supposed to account for a stepwise reduction of the number of independently oscillating mode packets. As an interesting application, the spectroscopic technique of intracavity optical-optical double resonance is discussed and demonstrated.

Deterministic chaos and dynamical instabilities in a multimode cw dye laser.

The dynamics of a cw pumped, multimode dye laser system have been experimentally investigated by measuring the mode correlation times ${t}_{\mathrm{mode}}$, the second-order dimension ${D}_{2}$ of the attractor of the system, and the corresponding second-order entropy ${K}_{2}$. Dynamical instabilities have been observed as discontinuous changes of ${t}_{\mathrm{mode}}$, ${D}_{2}$, and ${K}_{2}$ at distinct values of the spectral power density P/\ensuremath{\Delta}\ensuremath{\lambda}. Over the whole investigated range of P/\ensuremath{\Delta}\ensuremath{\lambda}, the analysis of the experimental data yields sufficient conditions for deterministic chaos. The dimensionality of the system and its degree of chaos have been found to depend on the spectral power density. The contributions of stochastic and of chaotic processes to the limited mode correlation time have been unraveled.

Kinetics of emission of individual modes by a multimode cw dye laser and its influence on the sensitivity of intracavity laser spectroscopy

An experimental study was made of the kinetics of emission of individual modes of a multimode cw dye laser. Fluctuations of the output radiation in the modes and reduction in the characteristic time of these fluctuations were observed when excess of the pumping rate above the threshold was increased. The only factor that determined the sensitivity of intracavity laser spectroscopy was the duration of emission of radiation in each mode.

Mode-correlation times and dynamical instabilities in a multimode cw dye laser.

Correlation times of mode amplitudes in a multimode cw dye-laser system have been measured using intracavity absorption spectroscopy. The dependence of the mode-correlation times on the spectral power density in the laser cavity has been investigated in detail. At low spectral power densities, surprising discontinuities are observed and interpreted as dynamical instabilities in the laser system. At high spectral power densities, the mode-correlation time approaches a constant value. These observations are described by a system of two nested, self-referential feedback loops explaining the behavior of the laser system. The resulting model is discussed within the concepts of generalized multistability and presumably chaotic behavior.

A cw dye laser for intracavity state selection of atomic and molecular gases

A simple standing-wave, multi-mode cw dye laser system with wide intracavity space for excitation of an appropriate target is described. The resonator contains 5 mirrors and 2 tuning elements from commercial lasers and features: (i) about 10 GHz bandwidth with 63 MHz mode separation; (ii) 5–30 W intracavity power in the range 535–800 nm; (iii) a nearly parallel, linearly-polarized expanded laser beam (radius about 3 mm) for target excitation. Efficient state selection is demonstrated for metastable Ne(3s 3P 2,0), Ar(4s 3P 2,0), Kr(5s 3P 2,0) atom beams, using Penning ionization electron spectrometry for detection. As an application, we report the fine-structure state dependence of the electron emission coefficients γ for normal impact of Ne ∗, Ar ∗, and Kr ∗ metastables on a gas covered polished stainless steel surface.

Polarization of an atomic sodium beam by laser optical pumping

A highly polarized $^{23}\mathrm{Na}$ atomic beam is produced by optical pumping with the use of either a multimode cw dye laser or a single-mode ring dye laser followed by a double-passed acousto-optic modulator. Electron-spin polarizations of 0.72 to 0.90 are obtained.

Saturation spectroscopy of hydrogen 1-011-011-01lines with a multi-mode cw dye laser

With an intense, broadband multi-mode cw dye laser collisional studies of Hα fine-structure resonances with saturated absorption are extended to He buffer gas pressures larger than 30 mbar (0°C). The broadening and shift of the two prominent Hα(2P−3D) transitions are measured in a (He+4% H) gas discharge. The absolute magnitude and the differences in the width of the lines are explained theoretically by different inelastic fine-structure transfer cross sections which can also be deduced from the pressure effect data. Nuclear polarization of hydrogen atoms by Hα optical pumping and polarization transfer to the H(1S) ground state via Ly-α decay and further applications of the multimode laser are discussed.

Multi-mode cw dye laser

An intense, frequency stable, multi-mode, standing wave cw dye laser of variable bandwidth (0.5 to 3 GHz) and large tuning range (>400 GHz) is described. The resonator of 70 to 100 cm length is a symmetric Z-configuration with the dye jet in the center and with a Lyot-filter and one thin etalon as colour and bandwidth selecting and tuning elements. The characteristics of the laser for the dyes C102, Rh101, and DCM, its use for nonlinear plasma spectroscopy of the atomic hydrogen H α and H α lines, and possible further applications are discussed.